Wells Score (DVT)

What This Calculator Measures

Estimates the pre-test probability of deep vein thrombosis to guide D-dimer testing and compression ultrasound.

How to Use

1. Assess each of the nine clinical items in the Wells criteria.
2. Select Yes for each criterion that is present.
3. Select whether an alternative diagnosis is at least as likely as DVT (subtracts 2 points).
4. Use the two-tier interpretation to guide testing.

Interpretation Guide

Two-tier: score ≤1 = DVT unlikely (negative high-sensitivity D-dimer safely excludes DVT); score ≥2 = DVT likely (proceed to compression ultrasound). Three-tier: ≤0 low, 1–2 moderate, ≥3 high probability.

Clinical Significance

Wells DVT criteria allow clinicians to stratify pre-test probability, safely using D-dimer to avoid unnecessary ultrasound while not missing clinically significant thrombosis.

When to Use

• Emergency department evaluation of suspected lower extremity DVT
• Deciding whether to order D-dimer before ultrasound
• Structuring the assessment of unilateral leg swelling or pain

When Not to Use

• Patients with a swollen leg and hemodynamic instability suggestive of phlegmasia
• When clinical suspicion is high regardless of the score
• As a stand-alone diagnostic test

Limitations

• The alternative-diagnosis item is subjective.
• Performance varies in populations with a high baseline DVT prevalence.
• A low score does not exclude DVT when clinical suspicion remains high.

Worked Example

A 55-year-old man is 2 weeks post hip surgery with a swollen, tender left leg, entire-leg swelling, calf swelling, and pitting edema. No alternative diagnosis is as likely as DVT.

Wells DVT score 5 — DVT likely. Proceed directly to compression ultrasound; D-dimer is not recommended.

Evidence

Source

Wells DVT Criteria

Reference

Wells PS, et al. Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis. N Engl J Med. 2003;349(13):1227-1235.

Reviewed By

MedCalcHub Clinical Team

Version

1.0

Updated

2026-08

1. Wells PS, et al. N Engl J Med. 2003;349(13):1227-1235.
2. Wells PS, et al. Lancet. 1995;345(8960):1326-1330.

References

1. Wells PS, et al. Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis. N Engl J Med. 2003;349(13):1227-1235. (Management Study)
2. Wells PS, et al. Accuracy of clinical assessment of deep-vein thrombosis. Lancet. 1995;345(8960):1326-1330. (Original Derivation)